JPH02156667A - Image reader - Google Patents

Abstract

PURPOSE:To avoid an influence of an electromagnetic noise from an inverter and a fluorescent lamp and to enhance an image quality by a method wherein a transparent electrode is formed on the surface of a color filter constituting an image reader and the electrode is grounded. CONSTITUTION:A refractive-index distribution type lens array 2, an image sensor 3 as a line sensor, a fluorescent lamp 4, an inverter 5, a carriage cover 6 and a color filter 7 are assembled in a carriage 1; a read unit 8 is constituted of all of them. A manuscript 9 is arranged in a position facing the sensor 3 in such a way that the array 2 is sandwiched; its image is read out. An important point in this constitution is a structure of the color filter 7; three transparent conductive films 10a to 10c composed of an oxide, an ITO or the like are formed on the surface of a glass base material in a vertical scanning direction; they are covered respectively with a green filter, a red filter and a blue filter 11a to 11c; the films are faced with a sliding face of the carriage 1 and are grounded. Thereby, a sufficient electromagnetic shielding effect is produced together with the cover 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the field of information processing and office equipment, and more particularly to image reading devices and copying machines.

[Prior Art] As a means for inputting image information into information processing equipment,
An image reading device is used. Generally, optical information of a document from which image information is to be obtained is converted into electromagnetic information by a photoelectric conversion means, that is, an image sensor, and the image information can be processed by an information processing device.

In an image reading device, a lens is generally used to form an image of optical information of a document onto an image sensor. Of the optical information, if only density information is read, only monochromatic image information can be handled, but by reading wavelength components as well, color image information can also be processed.

A number of methods for reading wavelength components have already been proposed or put into practical use. Typical methods include a method of switching color filters and a method of using an image sensor provided with a color filter array mask, and these methods are called single-chip methods. There is also a three-plate type that uses three image sensors that are divided into three wavelength components by a dichroic prism.

[Problems and Objects to be Solved by the Invention] In a color image reading device of a type in which color filters are switched, it is necessary to use a white light source as a light source, and generally a fluorescent tube that emits white light is used. When fluorescent tubes are lit using a commercial AC power supply, the power frequency is 2
It blinks at double the frequency, and this blinking appears as brightness and darkness in the image in the reading results. For this reason, an inverter is usually used to turn on the fluorescent tube at high frequency to prevent the effects of blinking the light source from appearing on the read image.

However, since the inverter boosts the voltage to over several hundred volts and oscillates at a high frequency of several tens of kilohertz, the inverter and fluorescent tube generate extremely high levels of electromagnetic noise. Optical system systems for image reading devices include the 1:1 magnification reduction system, but in recent years, it has become mainstream to design a compact optical system that includes a light source and image sensor as a reading unit. It has become. In this case, since the inverter and fluorescent tubes are also placed inside the reading unit, the spatial distance between the inverter and fluorescent tubes and the image sensor is inevitably small, and the electromagnetic noise generated from the inverter and fluorescent tubes is transmitted to the image sensor's image signal. as a result, the quality of the read image deteriorates.

As a countermeasure against this problem, a method is taken in which the frame or base member of the reading unit is made of a material that has an electromagnetic shielding effect. However, since only light-transmissive materials such as glass or plastic can be placed in the part that hits the optical path, it is not possible to provide an electromagnetic shielding effect, and the device is defenseless against electromagnetic noise that propagates through the optical path.

The present invention is intended to solve this problem, and aims to provide an image reading device that has good read image quality and is not affected by electromagnetic noise generated from the inverter or fluorescent tube even when an inverter is used. .

[Means for Solving the Problems] In order to solve the above problems, in the present invention, a transparent electrode is formed on the surface of a color filter, and the transparent electrode is grounded.

[Function] In the present invention, a color filter is used for wavelength selection. The color filters used are very common blue, green, and red filters. A transparent electrode is formed on the surface of the color filter, and by grounding this transparent electrode, an electromagnetic shielding effect is created in the transparent electrode, which prevents electromagnetic noise generated from the inverter and fluorescent tubes that reach the image sensor through the optical path. It can be prevented.

Further, although various methods can be considered for manufacturing a color filter, by using a transparent electrode as an electrode for electrodeposition, it becomes possible to manufacture a color filter by an electrodeposition method.

[Example] The present invention will be explained in detail according to an example. FIG. 1 is a structural sectional view of an image reading unit according to an embodiment of the present invention. Carriage 1 has a gradient index lens array (
(trade name SELFOC lens) 2, an image sensor 3, a fluorescent tube 4, an inverter 5, a carriage cover 6, and a color filter 7 are incorporated, and the reading unit 8 is made up of these as a whole.

The image sensor 3 is a line sensor, and the longitudinal direction of each component is perpendicular to the paper/surface, which coincides with the main scanning direction for image reading. The horizontal direction on the paper is the sub-scanning direction.

The original 9 is placed at a position facing the image sensor 3 with the gradient index lens array 2 in between.

The carriage 1 and the carriage cover 6 are made of a conductive material, such as metal or conductive plastic. Further, the carriage 1 is electrically connected to the frame ground or the signal ground through other image reading device components (not shown) or wiring (not shown).

FIG. 2 is a perspective view of the color filter 7 shown in FIG. 1. The base material of the color filter 7 is glass, and on its surface, transparent conductive films 10a, 1°b, and 10c are formed divided into three regions in the sub-scanning direction as shown in the figure. The material of the transparent conductive film 10 may be tin oxide or IT.
O etc. can be used. Transparent conductive film ioa, 10b, 1
Green, red, and blue pigments are deposited on 0c by electrodeposition, respectively.
They are insolubilized to form a green filter lla, a red filter 11b, and a blue filter llc. Since the electrodeposition technique itself is a well-known technique, its explanation will be omitted. The color filters 7 can be freely moved in the sub-scanning direction inside the carriage 1, and each filter color is selected depending on the relative position with respect to the carriage 1, and the wavelength to be used is determined. Further, the sliding surface of the color filter with the carriage 1 is a transparent conductive film 10, and the carriage 1 and the transparent conductive @10 are electrically connected. Common methods for producing color filters include a method using colored glass, a dyeing method using dye, a gelatin filter method, and an electrodeposition method using pigments as described in this embodiment. The method using colored glass requires a large number of processing steps and tends to be expensive. Dyeing methods and gelatin filters have problems in terms of environmental resistance, light resistance, etc. The electrodeposition method requires fewer processing steps and is less expensive, and because it uses pigments, it has good environmental resistance and light resistance.

In image reading according to the present embodiment, main scanning is performed by the signal reading and sending operation of the image sensor 3, which is a line sensor. Sub-scanning is performed by relative movement of the reading unit 8 and original document 9, but in many cases, the original document 9 is fixed and the reading unit 8 is moved. green filter l
Color reading can be performed by reading the same original three times by selecting the red filter lla, the red filter llb, and the red filter llc, respectively.

High-level electromagnetic noise is generated from the fluorescent tube 4 and inverter 5, but according to the configuration of this embodiment, the carriage 1 and carriage cover 6 have an electromagnetic shielding effect, so the signal from the image sensor 3 is not affected by electromagnetic noise. becomes difficult to receive. Moreover, since the transparent conductive l110 of the color filter is electrically connected to the frame ground and signal ground through the carriage 1, the color filter 7 also produces an electromagnetic shielding effect, and conventionally electromagnetic noise from the optical path could not be prevented, but this According to the embodiment, this can be prevented, and the signal of the image sensor 3 is hardly affected by electromagnetic noise.

This example describes the case where the transparent conductive film is also used as an electrode film for electrodeposition, but of course the same effect can be expected by simply forming a transparent conductive film on the surface of a general color filter. can.

[Effects of the Invention] According to the present invention, an image reading device capable of obtaining high image quality that is not affected by electromagnetic noise generated from an inverter or a fluorescent tube can be realized by adding a slight processing such as forming a transparent electrode. Furthermore, by using this transparent electrode as an electrode for electrodeposition, a color filter can be easily manufactured at low cost.

...Color filter, 8...Reading unit, 9
...manuscript, 10a, 10b, 10c...transparent conductive film, lla...green filter, llb...red filter, llc...blue filter and above Applicant: Seiko Epson Corporation Company agent Patent attorney Kisanbe Meiki and 1 other person

[Brief explanation of the drawing]

FIG. 1 is a structural sectional view showing one embodiment of the present invention. FIG. 2 is a perspective view of the color filter.

Claims (2)

[Claims] (1) In an image reading device that has a light source, a lens, a plurality of color light transmission filters, and an image sensor, and reads an image by sequentially selecting the light transmission filters, a transparent conductive film is formed on the surface of the light transmission filter. . An image reading device, wherein the transparent conductive film is grounded. (2) The image reading device according to item 1, wherein the light transmission filter has a pigment electrodeposited on the surface of a transparent conductive film.